What motorcycle boots are you looking at that are so massively bulky and heavy that you don't want to wear them? Racing boots are massively protective, but also massive and expensive. My ex wears BMW All-Around boots - mid high cut, fits under jeans, waterproof and reasonably protective. Comfortable walking, too.

The BMW All-Around is a great boot for the money. They area also comfortable enough to wear while walking around town. They cost a hell of a lot less than any other BMW boot and I'm not sure why that is. I was very happy with mine. I wore a hole in the sole and just replaced them with Santiagos which offer a lot better protection but at the expense of walking comfort.